1. Field of the Invention
The present invention relates generally to video encoding. More particularly, the present invention relates to a method and apparatus for hierarchical bi-directional intra-prediction in a video encoder.
2. Description of the Related Art
Video compression is used in many current and emerging products, such as digital television set-top boxes (STBs), high definition television (HDTV) decoders, digital versatile disk (DVD) players, BLU-RAY disc players, digital camcorders, personal computers, and the like. Without video compression, digital video content can be extremely large, making it difficult or even impossible for the digital video content to be efficiently stored, transmitted, or viewed. There are numerous video coding methods that compress digital video content. Consequently, video coding standards have been developed to standardize the various video coding methods so that the compressed digital video content is rendered in formats that a majority of video decoders can recognize. For example, the Motion Picture Experts Group (MPEG) and International Telecommunication Union (ITU-T) have developed video coding standards that are in wide use. Examples of these standards include the MPEG-1, MPEG-2 (ITU-T H.262), MPEG-4, ITU-T H.261, ITU-T H.263, and ITU-T H.264 standards.
Video encoding standards, such as MPEG standards, typically achieve data compression by utilizing various coding techniques, such as spatial and temporal prediction, transform and quantization, entropy encoding, and the like. Prediction in video encoders is typically includes both inter-prediction and intra-prediction for improving coding efficiency. Inter-prediction exploits the temporal correlation between images of video, whereas intra-prediction exploits the spatial correlation of pixels within an image of video. Both types of prediction are typically performed on blocks of pixels.
For intra-prediction, the prediction of a block is formed by extrapolating from neighboring samples of previously coded and reconstructed blocks, and then the difference between the block and its prediction is coded. Such a technique, however, does not work well with images having complex textures. Furthermore, the farther the pixels being predicted are from the surrounding pixels, the greater the error in prediction.
Accordingly, there exists a need in the art for intra-prediction in a video encoder that can overcome the aforementioned deficiencies.